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/* Author: Ioan Sucan */

#ifndef OMPL_BASE_SPACE_STATE_SAMPLER_
#define OMPL_BASE_SPACE_STATE_SAMPLER_

#include "ompl/base/State.h"
#include "ompl/util/RandomNumbers.h"
#include "ompl/util/ClassForward.h"
#include <vector>
#include <boost/noncopyable.hpp>

namespace ompl
{
    namespace base
    {

        ClassForward(StateSpace);

        /** \brief Forward declaration of ompl::base::StateSampler */
        ClassForward(StateSampler);

        /** \class ompl::base::StateSamplerPtr
            \brief A boost shared pointer wrapper for ompl::base::StateSampler */

        /** \brief Abstract definition of a state space sampler. */
        class StateSampler : private boost::noncopyable
        {
        public:

            /** \brief Constructor */
            StateSampler(const StateSpace *space) : space_(space)
            {
            }

            virtual ~StateSampler(void)
            {
            }

            /** \brief Sample a state */
            virtual void sampleUniform(State *state) = 0;

            /** \brief Sample a state near another, within specified distance */
            virtual void sampleUniformNear(State *state, const State *near, const double distance) = 0;

            /** \brief Sample a state using a Gaussian distribution with given \e mean and standard deviation (\e stdDev) */
            virtual void sampleGaussian(State *state, const State *mean, const double stdDev) = 0;

        protected:

            /** \brief The state space this sampler samples */
            const StateSpace     *space_;

            /** \brief An instance of a random number generator */
            RNG                  rng_;
        };

        /** \brief Definition of a compound state sampler. This is useful to construct samplers for compound states. */
        class CompoundStateSampler : public StateSampler
        {
        public:

            /** \brief Constructor */
            CompoundStateSampler(const StateSpace* space) : StateSampler(space), samplerCount_(0)
            {
            }

            /** \brief Destructor. This frees the added samplers as well. */
            virtual ~CompoundStateSampler(void)
            {
            }

            /** \brief Add a sampler as part of the new compound
                sampler. This sampler is used to sample part of the
                compound state. When sampling near a state, the
                compound sampler calls in to added samplers. The
                distance passed to the called samplers is adjusted
                according to the specified importance. */
            virtual void addSampler(const StateSamplerPtr &sampler, double weightImportance);

            virtual void sampleUniform(State *state);

            virtual void sampleUniformNear(State *state, const State *near, const double distance);

            virtual void sampleGaussian(State *state, const State *mean, const double stdDev);

        protected:

            /** \brief The samplers that are composed */
            std::vector<StateSamplerPtr> samplers_;

            /** \brief The weight of each sampler (used when sampling near a state) */
            std::vector<double>          weightImportance_;

        private:

            /** \brief The number of samplers that are composed */
            unsigned int                samplerCount_;

        };

    }
}


#endif
